A. Field
The invention relates to a lock for irrotationally locking a motor-vehicle steering column enclosed by a tubular housing, said lock being fitted with a locking element displaceable in a to-and-fro manner between a locked and a released position and with a drive motor driving said locking element.
B. Related Art
A number of different designs already are known for means irrotationally locking motor-vehicle steering columns.
Illustratively, as regards one design of the prior art, the locking element and the said drive motor are configured at the lower steering-column end within a common housing. The steering column runs through the associated tubular housing, and through an opening in a metal floor panel of the motor vehicle and through said common housing screwed onto the metal floor panel on the side away from said tubular housing. The locking element encloses the steering column and is supported in axially displaceable but irrotational manner in said common housing and is fitted with locking teeth which may be made to mesh with matching locking teeth of the steering column. Said drive motor is an electric motor affixed to the inside of said common housing and cooperates by a mechanical linkage or by a lever with said locking element (EP 0 265 826 B).
In another known design of the kind of lock discussed herein, the locking element and the drive motor are mounted close to one another and outside the tubular housing enclosing the steering column. The locking element is in the shape of a bush and is mounted on the tubular housing in an axially displaceable manner and is fitted with at least one resilient locking tooth that can be made to mesh with rigid locking teeth of the steering column. Said drive motor is an electric motor externally affixed to the tubular housing and by means of a cam-collar cooperates with the locking element in order to displace the latter against the force of a helical compression spring enclosing the steering column in a manner such that the locking element""s locking tooth can be disengaged from the steering column""s locking teeth to allow rotation of the steering column. The cam-collar is rotatably supported on the tubular housing and is fitted with circumferential teeth meshing with a pinion affixed on the shaft of the electric motor (DE 195 00 682 C).
Again a design of the above discussed type of lock is known wherein the locking element and the drive motor are configured near each other in a common housing through which the steering column runs. The locking element consists of a shaft rotatably supported inside the housing and fitted with two radially projecting locking protrusions. The shaft runs tangentially relative to a locking ring which is affixed to the steering column and which is fitted with locking teeth with which the shaft""s locking protrusions can be made to engage. The drive motor is an electric motor affixed in the housing and cooperating via a gearing unit with said shaft (DE 196 21 326 C).
The objective of the present invention is a lock of the initially mentioned kind which is characterized by compactness, by offering extraordinary vehicle theft-protection, by unhampered ability to telescope of the steering pillar composed of steering column and tubular housing, and by preserving the driver in the event of accident from knee injuries because it is located outside the region containing the knees.